Y. Ōnuki

Itinerant to localized transition of f electrons in the antiferromagnetic superconductor UPd 2 Al 3

Itinerant to localized transition of f electronsxa0in the antiferromagnetic superconductorxa0UPd 2 Al 3

Miniature ceramic-anvil high-pressure cell for magnetic measurements in a commercial superconducting quantum interference device magnetometer

A miniature opposed-anvil high-pressure cell has been developed for magnetic measurement in a commercial superconducting quantum interference device magnetometer. Non-magnetic anvils made of composite ceramic material were used to generate high-pressure with a Cu-Be gasket. We have examined anvils with different culet sizes (1.8, 1.6, 1.4, 1.2, 1.0, 0.8, and 0.6 mm). The pressure generated at low temperature was determined by the pressure dependence of the superconducting transition of lead (Pb). The maximum pressure P(max) depends on the culet size of the anvil: the values of P(max) are 2.4 and 7.6 GPa for 1.8 and 0.6 mm culet anvils, respectively. We revealed that the composite ceramic anvil has potential to generate high-pressure above 5 GPa. The background magnetization of the Cu-Be gasket is generally two orders of magnitude smaller than the Ni-Cr-Al gasket for the indenter cell. The present cell can be used not only with ferromagnetic and superconducting materials with large magnetization but also with antiferromagnetic compounds with smaller magnetization. The production cost of the present pressure cell is about one tenth of that of a diamond anvil cell. The anvil alignment mechanism is not necessary in the present pressure cell because of the strong fracture toughness (6.5 MPau2009m(1∕2)) of the composite ceramic anvil. The simplified pressure cell is easy-to-use for researchers who are not familiar with high-pressure technology. Representative results on the magnetization of superconducting MgB(2) and antiferromagnet CePd(5)Al(2) are reported.

Anomalous Temperature Dependence of Lower Critical Field in Ultraclean URu2Si2

To investigate a mysterious superconducting state of URu 2 Si 2 embedded in the so-called hidden order state, the lower critical field H c1 is precisely determined down to 55 mK for H ∥ a and H ∥ c . For this purpose, the positional dependence of the local magnetic induction is measured on ultraclean single crystals ( T c = 1.4 K) with residual resistivity ratio exceeding 700. We find that the temperature dependence of H c1 significantly differs from that of any other superconductors. The whole H c1 ( T ) for H ∥ a are well explained by the two superconducting gap structures with line and point nodes, which have been suggested by the recent thermal conductivity and specific heat measurements. On the other hand, for H ∥ c , a change of slope with a distinct kink in H c1 ( T ), which cannot be accounted for by two gaps, is observed. This behavior for H ∥ c sharply contrasts with the cusp behavior of H c1 ( T ) associated with a transition into another superconducting phase found in UPt 3 and U 1- x Th x Be ...

Single crystal growth and characterization of URu2Si2

We review recent progress in single crystal growth and study of electronic properties in . Czocharalski pulling, using purified uranium metal and subsequent annealing under ultra-high vacuum, is successfully applied to this compound, and it yields the highest residual resistivity ratio. These high-quality single crystals allow us to investigate Fermi surfaces using quantum oscillation and to make detailed transport measurements at low temperature.

Unconventional superconductivity and quantum criticality in the heavy fermions CeIrSi3 and CeRhSi3

Superconductivity and magnetism are mutually exclusive in most alloys and elements, so it is striking that superconductivity emerges around a magnetic quantum critical point (QCP) in many strongly correlated electron systems (SCES). In the latter case superconductivity is believed to be unconventional and directly influenced by the QCP. However, experimentally unconventional superconductivity has neither been established nor directly been linked to any mechanism of the QCP. Here we report measurements in the heavy-fermion superconductors CeIrSi

T-dependent Nuclear Hyperfine Coupling at the In Site in CeIrIn5

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Magnetic and superconducting properties of and without inversion symmetry

and CeRhSi

Magnetic and electronic properties in and (T: transition metal)

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Anisotropic magnetic properties of single crystal

. The measurements were performed with a newly developed system, first of its kind, that allows high-resolution studies of the superconducting gap structure under pressure. Superconductivity in CeIrSi

Soft X-Ray Magnetic Circular Dichroism Study of Ferromagnetic Uranium Compounds

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